OK. My managed switch came in, and I started doing some testing. I am seeing some improvements, generally I can get 20-30MB/sec (140-200Mb/sec) using iperf and file copying.
I can see that CPU utilization on both sides is pretty low. and no oddities on the switch (collisions, dropped packets, or any other warning). Just low bandwidth.
Incidentally, using iperf, UDP is MUCH worse; single digit Mbits/sec. Seriously.
Now what?
-Scott
----- Original Message -----
From: "Scott Chapman" <scottchapman@xxxxxxxxxxxxxx>
To: "Hansang Bae" <hbae@xxxxxxxxxx>
Cc: "Community support list for Wireshark" <wireshark-users@xxxxxxxxxxxxx>
Sent: Tuesday, March 17, 2009 4:36:01 PM GMT -05:00 US/Canada Eastern
Subject: Re: [Wireshark-users] Slow gigabit network
I have checked all the obvious things (CPU is under utilized, and I have fiddled around with some of the driver settings that might be related like buffer sizes, and off loading and the like).
I am expecting to get a managed HP switch in a couple of days, so perhaps that could shed some light (or just fix it outright!).
-Scott
----- Original Message -----
From: "Hansang Bae" <hbae@xxxxxxxxxx>
To: wireshark-users@xxxxxxxxxxxxx
Cc: "Scott Chapman" <WireShark@xxxxxxxxxxxxxxxxx>, "Community support list for Wireshark" <wireshark-users@xxxxxxxxxxxxx>
Sent: Tuesday, March 17, 2009 4:30:59 PM GMT -05:00 US/Canada Eastern
Subject: Re: [Wireshark-users] Slow gigabit network
At 11:09 AM 3/10/2009, Scott Chapman wrote:
>I have experimented with forcing 1000/full explicitly on both sides with out any effect.
>
>Incidentally, I do occasionally get 20MB/sec.
>
>Before I go buy anew switch I was hoping to learn how to use wireshark to see what is going on, perhaps to help point the finger somewhere...
Scott,
Divide and conquer. I don't recall if you tried netperf or UDP based testing tools or not. The slowness could be your NIC, it could be the protocol in use, or it could be the switch. Does performance stats (like perfmon if using wintel) show that cpu is shooting high? Do you have tcp off loading enabled? Did you try disabling it? Did you try applying the latest NIC drivers?
Did you try using ports 1 and 2 (not 1 and 25)? If the are right next to each other, did you try separating them (if on 1 and 2, move it to 1 and 13) to rule out ASIC based issues? Have you monitored netstat or switch counters (if avail) for packet drops?
hsb
